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Old 05-22-2007, 04:02 PM   #1
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Default Need help wiring up aem wideband to megasquirt

Alright guys, I just got an aem wideband and want to be able to hook it up to the megasquirt pnp and have it work. I suck with electronics and get nothing but confused. These are instructions Jerry at diyautotune sent me but it got me even more confused. Can anyone help or give some more info/pix or anything?


"As for the wideband just install it according to it's docs, share ground with the ECU (you'll strip one of the ECU harnesses ground wires to do this, and use this for the wideband computers ground, if it has a separate heater ground put that elsewhere), wire the output from the wideband to the MS o2 input (easiest way may be to simply tie it into the stock o2 sensor wire), unlplug the stock O2 sensor so it won't interfere, and then setup the MSPNP for the AEM wideband in the Configurator and in MegaTune." -Jerry
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Old 05-22-2007, 04:09 PM   #2
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what don't you understand? hooking it up or configuring the ms?

neither is difficult. install the wb gauge per its directions. it's going to need +12v and ground. both are at the ecu harness. then you'll need to hook up the wb analog out to the ms. there are 2 options for doing so, both explained in the manual. i snipped the stock nb wire, but it would have been smarter to use the middle connector.

then you'll need use the ms configurator, it's obvious enough how to use, and there are a couple of settings changes in megatune. it's all in the manual, follow it step by step.
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Old 05-22-2007, 04:13 PM   #3
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configuring the ms isnt the problem...my issue was hooking it up and actually wiring it up.
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Old 05-22-2007, 04:27 PM   #4
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the aem has four wires....correct?

black red white and blue.

black is ground, MS has plenty of those (even the frame, block, etc.)

red is power, MS has plenty of those

white goes to O2. So you either splice into the wire for it and disconnect the O2 sensor. Or leave it installed and simply cut the O2 wire (pink) and wire it to the White AEM wire.

blue is unused.
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Old 05-22-2007, 04:47 PM   #5
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hmm braineak interesting and **** i hate being a newb at this. Jerry just sent me an email saying I should tap the ecu harness. According to Jerry 2A-2D are grounds, and 1B is power.



So that being said tell me if this seems right. I should

tap BLACK AEM wire to 2A-2D (one of them)
tap RED AEM wire to 1B

and as far as the 02 sensor goes, If i want to leave the O2 sensor I cut the pink O2 sensor wire and tap in the white aem line on it ?


Sorry for being annoying as **** and asking a million questions.
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Old 05-22-2007, 04:58 PM   #6
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sounds right,

the NA O2 pin is 2N (red/blu), slice onto that, and just disconnect the oem sensors from the harness near the coils.
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Old 05-22-2007, 05:41 PM   #7
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is that a good source or accurate reading by connecting your aem wideband to pin 2n and disconnect the nb,whats the pin #10 on pnpms for alternate wbo2 can he just connect thru there.??
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Old 05-22-2007, 05:52 PM   #8
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as per thier instructions

Quote:
There are two ways of connecting the controller to the MSPNP. You can either connect the analog output to pin 10 of the MSPNP center connector, or you can cut and splice the oxygen sensor signal wire to the analog output. If you use pin 10 for wideband input, you must disconnect the stock oxygen sensor. Do not ground the oxygen sensor wire if you disconnect it; leave it completely unconnected and taped off if necessary (make sure it can’t short to ground or anything else).
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Old 05-22-2007, 06:46 PM   #9
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Quote:
Originally Posted by Braineack View Post
as per thier instructions
so I need power, ground, signal to the stock wire, and let the other wire be?

What should I use for the switched power source? Do I need to create a relay circuit for the o2, knocksense, gauges, and whatever else? I don't know much about the miata's electrical system.
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Old 05-22-2007, 06:55 PM   #10
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read post #5 and then go ahead and erase your post...
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Old 06-14-2008, 02:21 AM   #11
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Quote:
Originally Posted by Braineack View Post
sounds right,

the NA O2 pin is 2N (red/blu), slice onto that, and just disconnect the oem sensors from the harness near the coils.
Newb question:

Where is the car getting the narrowband signal from, if the oem O2 sensor plug is disconnected?

When I look at BEGI's DP, I notice there's a place for a NB and an optional WB bung. Why even place a NB bung if the oem O2 sensor just gets disconnected?

I'm pretty sure I'm thinking of this wrong. Can someone please school me?

Last edited by kenzo42; 06-14-2008 at 02:40 AM.
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Old 06-14-2008, 02:25 AM   #12
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I'm 90% sure mine had
red---power
black---ground
white---serial output
Pink--- 0-5V out
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Old 06-14-2008, 03:57 AM   #13
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Quote:
Originally Posted by kenzo42 View Post
Where is the car getting the narrowband signal from, if the oem O2 sensor plug is disconnected?
With a standalone Megasquirt, no narrowband signal is needed.


Quote:
When I look at BEGI's DP, I notice there's a place for a NB and an optional WB bung. Why even place a NB bung if the oem O2 sensor just gets disconnected?
Because a lot of people run both an NB and a WB sensor. Those using piggyback ECUs, those using old-school fuel management with a gaug-only WBO2 sensor, etc. Only those of us with a full standalone ECU (or who trust the LC-1's simulated narrowband output) can discard the narrowband sensor altogether.
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Old 06-14-2008, 04:01 AM   #14
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Thanks Joe.

Since I will be running MS in parallel and will need a NB since I'm not standalone, what is the correct way to wire the UEGO into the MS?

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Originally Posted by Joe Perez View Post
With a standalone Megasquirt, no narrowband signal is needed.


Because a lot of people run both an NB and a WB sensor. Those using piggyback ECUs, those using old-school fuel management with a gaug-only WBO2 sensor, etc. Only those of us with a full standalone ECU (or who trust the LC-1's simulated narrowband output) can discard the narrowband sensor altogether.
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Old 06-14-2008, 04:07 AM   #15
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Quote:
Originally Posted by kenzo42 View Post
Since I will be running MS in parallel and will need a NB since I'm not standalone, what is the correct way to wire the UEGO into the MS?
Ok, first off, understand that the instructions you quoted earlier were for an MSPNP, which is a standalone.

For a parallel install, leave the stock NB sensor and wiring completely alone, and simply connect the wideband's 0-5 volt output to the Megasquirt's O2 sensor input, and configure the MS software appropriately. That's it- no cutting, no splicing, just one connection.

Extra point: make sure the WBO2 controller is grounded to the same point as the MS.
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Old 06-14-2008, 04:18 AM   #16
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I didn't realize it would be that easy.

Does parallel MS even need an O2 signal on pin 23 then, assuming hypothetically it wasn't occupied by the WB?

Quote:
Originally Posted by Joe Perez View Post
Ok, first off, understand that the instructions you quoted earlier were for an MSPNP, which is a standalone.

For a parallel install, leave the stock NB sensor and wiring completely alone, and simply connect the wideband's 0-5 volt output to the Megasquirt's O2 sensor input, and configure the MS software appropriately. That's it- no cutting, no splicing, just one connection.

Extra point: make sure the WBO2 controller is grounded to the same point as the MS.
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Old 06-14-2008, 04:34 AM   #17
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Quote:
Originally Posted by kenzo42 View Post
Does parallel MS even need an O2 signal on pin 23 then, assuming hypothetically it wasn't occupied by the WB?
Define "need."

You don't technically need beer in order to survive, but there's no logical reason to go without it.

Likewise, if you run with no O2 correction (EGO authority = 0) then no, the MS does not need an O2 sensor input. But there's no good reason not to hook it up- if you have no O2 sensor at all then your idle and cruise mixture will never be perfect. Even if you don't have a wideband, connecting the narrowband sensor will allow you to run closed-loop in the lower MAP rows.
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Old 06-14-2008, 05:27 AM   #18
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I'm a dimwit in the electronics department, so please bear w/ me.

Quote:
Originally Posted by Joe Perez View Post
For a parallel install, leave the stock NB sensor and wiring completely alone, and simply connect the wideband's 0-5 volt output to the Megasquirt's O2 sensor input.
If I leave all the NB wiring alone, how can I run MS's O2 correction if there's no NB wiring going to MS?

Quote:
Even if you don't have a wideband, connecting the narrowband sensor will allow you to run closed-loop in the lower MAP rows.
Where will the NB connect to, since the WB now occupies pin 23?

Thanks again. I'm a fool.
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Old 06-14-2008, 11:56 AM   #19
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Quote:
Originally Posted by kenzo42 View Post
I'm a dimwit in the electronics department, so please bear w/ me.



If I leave all the NB wiring alone, how can I run MS's O2 correction if there's no NB wiring going to MS?



Where will the NB connect to, since the WB now occupies pin 23?

Thanks again. I'm a fool.
The WB02 goes to the MS, the NB goes to the stock ECU.
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Old 06-14-2008, 12:21 PM   #20
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Quote:
Originally Posted by kotomile View Post
The WB02 goes to the MS, the NB goes to the stock ECU.
What he said.


In a parallel install, the Megasquirt is in full command of fuel. It wants to see the WBO2 to determine where the mixture is so that EGO correction can work. The Megasquirt does not need a narrowband sensor IF it is connected to a wideband sensor.

The stock ECU cannot read a wideband output, only a narrowband. From an operational standpoint, it doesn't really need an O2 sensor signal (since it's not controlling fuel anymore) however it doesn't know this and will throw a CEL if you don't give it one.

So, the wideband connected to the MS is what's actually controlling the fuel, the narrowband connected to the stock ECU is there just to keep it happy.

If you do not have a wideband, then the narrowband sensor can be connected to both devices, however this is a sub-optimal situation as you won't be able to tune for any mixture other than 14.7:1.
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